ln order to appraise scientifical y the heavy metal contamination in waste-land of coalmine tailing in Mingshan of Guangdong, the 5 soil samples in wasteland of coalmine tailing were col ected in November 2010 to Marc...ln order to appraise scientifical y the heavy metal contamination in waste-land of coalmine tailing in Mingshan of Guangdong, the 5 soil samples in wasteland of coalmine tailing were col ected in November 2010 to March 2011. The 7 heavy metals content in the contaminated soil was measured by atomic absorption spec-trophotometry. The results showed the pH of the wasteland soil ranged from 2.87 to 6.16, and the soil was relatively infertile. The soil was mainly pol uted by Cd and Mn. The Cd content in wasteland soil ranged from 0.759 mg/kg to 3.109 mg/kg with an average content of 2.052 mg/kg, which was much higher than the standard content. The Mn content ranged from 387.057 to 488.660 mg/kg with an average content of 421.215 mg/kg, which was much higher than the standard content. The Nemerow integrated pol ution indexes showed the sample 1, sample 4 and sample 5 were of heavy pol ution, and sample 2 and sample 3 were of moderate pol ution.展开更多
The changes of vegetation compositions, plant species diversity, species important value and succession of plant community were studied on waste dumps in Haizhou opencast coalmine which is located in the west of Liaon...The changes of vegetation compositions, plant species diversity, species important value and succession of plant community were studied on waste dumps in Haizhou opencast coalmine which is located in the west of Liaoning Province, China (41°41(-42°56( N, 121°1(-122°56(E). Four kinds of terraces with different ages (5, 10, 20 and 40 years) were selected for investigation of plants. Total of 63 species of natural colonized plants were recorded on the waste dump and they belong to 23 families. The main families were Compositae (15 species), Fabaceae (11 species) and Leguminosae (8 species), which accounted for 54.0% of total species and play an important role in natural vegetation recovery in waste dump area. The dominant species on 5-, 10-, 20-, 40-year-old terraces were Tribulus terrestris + Echinochloa hispidula + Salsola collina, Echinochloa hispidula + Artemisia sieversiana + Artemisia scoparia, Echinochloa hispidula + Clinelymus dahuricus + Artemisia scoparia + Artemisia sieversiana + Melilotus officinalis, Clinelymus dahuricus+Phragmites communis + Echinochloa hispidula+ Setaria viridis, respectively. According to the important value of species calculated. It is determined that Tribulus terrestris can act as pioneer species on waste dump and Clinelymus dahuricus, Phragmites communis and Echinochloah hispidula are important dominant species in vegetation restoration in Haizhou opencast coalmine. The study results can provide scientific basis for selecting and disposing appropriately plant species and rehabilitating vegetation on waste dumps of coalmine.展开更多
The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect c...The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.展开更多
This paper describes the procedures for design of supports and stabilization measures in the roadways.The procedures are based on the system developed in Ostrava-Karvina coal basin in Czech Republic.The calculation of...This paper describes the procedures for design of supports and stabilization measures in the roadways.The procedures are based on the system developed in Ostrava-Karvina coal basin in Czech Republic.The calculation of load bearing capacity of roadway supports contains the period of roadway construction and mining in the vicinities,based on the size of the natural rock arch.The loading of supports during mining comes from a stress wave in the rock mass in the forefront of coalface and the caving area of mined-out panel.The input data for the calculation method are deduced according to in-situ measurements of convergence and displacement in the roadways.展开更多
Objective Material exchange between magma and coal has recently received much attention, with published studies dedicated mainly to intrusion-related geochemical anomalies(An et al., 2017). It is found that magmatism ...Objective Material exchange between magma and coal has recently received much attention, with published studies dedicated mainly to intrusion-related geochemical anomalies(An et al., 2017). It is found that magmatism not only alters the chemical compositions of coal seams, but also brings new minerals to natural coke. Although some studies have related magmatic water to secondary minerals in the natural coke, the mineral formation展开更多
The forms of roof break,roof fall,and effects of the region scope in a fully mechanizedtop-coal caving (FMTC) face of the 101 fully-mechanized top coal caving face ofthe Tingnan Coalmine were analyzed by UDEC and FLAC...The forms of roof break,roof fall,and effects of the region scope in a fully mechanizedtop-coal caving (FMTC) face of the 101 fully-mechanized top coal caving face ofthe Tingnan Coalmine were analyzed by UDEC and FLAC^(3D) software.The analysis resultconfirms the phenomenon of roof falling,roof-off-strata,roof breaking,first weighting,periodicweighting and stress concentration,redistributions of surrounding rock and so on.Itprovides the gist to analyze the law of roof movement,characteristic of confining pressure,and to determine the formative structure forms of the immediate roof and main roof duringthe caving process.These results and the underground pressure observation results are inagreement.展开更多
The present study reflects upon the results of substantial program of two-dimensional Finite Element Method （FEM） numerical analyses of the open pit that links to slope angle optimization associated with the safety ...The present study reflects upon the results of substantial program of two-dimensional Finite Element Method （FEM） numerical analyses of the open pit that links to slope angle optimization associated with the safety factor of the pit slope of a coal mine in Bangladesh. In the present analyses, two types of models have been presented. The first model estimates safety factor without seismic effect on the overall pit slope of the model; the second model incorporates safety factor with seismic stability of the model. The calculated optimum slope angle of the first model is 31% with a rational safety factor of 1.51, prior to the seismic effect. However, the value is reduced to 0.93, 0.82, and 0.72, after we applies the seismic effect in the second model with M6, M6.5, and M7, respectively. Finally, our modeling results emphasize that for the case of the proposed Phulbari coalmine, there is extremely high prospect for causing massive slope failure along the optimum pit slope angle with 31% if the mine area felt seismic shaking, like the Sikkim （in northern India） earthquake with M6.9 on September 18, 2011.展开更多
The occurrence state of methane is mostly controlled by coalfield geologicalstructures.The coal-bearing strata at Qidong coalmine experienced many tectonic cyclessince their formation.The gas content made by the compl...The occurrence state of methane is mostly controlled by coalfield geologicalstructures.The coal-bearing strata at Qidong coalmine experienced many tectonic cyclessince their formation.The gas content made by the complicated structural geologic systemat the coalfield is very different, which is obviously higher on the north side of the Weimiaofracture belt than that on the south side and near itself.This thesis discussed the gas occurrenceregularity based on the geometric characteristics of the geological structure andits regional tectonic evolution.This study can provide a foundation for coalfield exploitationand deal with coal and gas outburst.展开更多
The ventilation system plays an essential role in underground workings, and improvements in dilution effect to stochastic methane build-up at cul-de-sac of a coalmine require the installation of mixed ventilation syst...The ventilation system plays an essential role in underground workings, and improvements in dilution effect to stochastic methane build-up at cul-de-sac of a coalmine require the installation of mixed ventilation system. For 4-12-1 I N02.8A centrifugal ventilation fan, the characteristic operating function of its mixed ventilation system is calculated from ventilation quantity and total pressure in the actual working status. At cul-de-sac of the reference coalmine, the evolution of methane concentration is a compound Poisson process and equivalent to a Brownian motion for Gaussian distributed increments. Solution of stochastic differential equation driven by mixed ventilation system, with dilution equation for its closure, provides parameters of mine ventilation system for keeping methane concentration within the permissible limit at cul-de-sac of the reference coalmine. These results intend to shed some light on application of blowing-sucking mixed ventilation systems in underground workings, and establish stochastic trends to consider methane control in coalmines.展开更多
Over the last decades,people from almost all over the world have realized that it is necessary to quickly develop strategies for the control and reduction of greenhouse gases (GHG) emissions.Among various GHGs,carbon ...Over the last decades,people from almost all over the world have realized that it is necessary to quickly develop strategies for the control and reduction of greenhouse gases (GHG) emissions.Among various GHGs,carbon dioxide (CO2) is the most abundant GHG.Its underground storage involves less risk and lower levels of dangerousness.The paper briefly describes the most effective technologies available in the market for background processes to storage (capture and transport) CO2,as well as the more secure solutions for its storage,in particular for the geological storage in carboniferous formations.This paper also outlines the methodologies for the risk assessment involved in storage of CO2,with a particular focus on cases where the injection is made into unminable coal seams and in abandoned coalmines.Methodologies used for risk analysis are described in detail with particular emphasis on Bayesian network (BN).Some applications regarding the risk assessment of CO2 injection processes and CO2 storage in carboniferous formations and contamination of aquifers are presented and analyzed.Finally,based on the applications of BN,several conclusions are drawn.展开更多
In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effe...In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.展开更多
Data modeling is the foundation of three-dimensional visualization technology. First the paper proposed the 3D integrated data model of stratum, laneway and drill on the basic of TIN and ARTP, and designed the relevan...Data modeling is the foundation of three-dimensional visualization technology. First the paper proposed the 3D integrated data model of stratum, laneway and drill on the basic of TIN and ARTP, and designed the relevant conceptual and logical model from the view of data model, and described the data structure of geometric elements of the model by adopting the object-oriented modeling idea. And then studied the key modeling technology of stratum, laneway and drill, introduced the ARTP modeling process of stratum, laneway and drill and studied the 3D geometric modeling process of different section laneways. At last, the paper realized the three-dimensional visualization system professionally coalmine-oriented, using SQL Server as background database, Visual C＋＋6.0 and OpenGL as foreground development tools.展开更多
3D visualization is one of major problems in “Digital Mine” theory and its technological research field. Through the observation of 3D geological models, spatial structural information, connected with the informatio...3D visualization is one of major problems in “Digital Mine” theory and its technological research field. Through the observation of 3D geological models, spatial structural information, connected with the information of production management hidden in geological data, could be detected. In order to meet the requirement of more efficient coal exploration, a case study of geological characters of the Daliuta Coal Mine is presented in which 3D visual models of the ground surface and geologic bodies are established on the basis of data models and data structures of 3D geology modeling. The main conclusions of this study are as follows: (1) Through analysis and organization of spatial discrete data, the drillhole database is designed with the data of the Daliuta mine; the connections amomg drillhole data are real- ized and displayed in a 3D environment. (2) Combining real data of the Daliuta mine, drillhole visualization is realized in a 3D environment by using the CoalMiner system. (3) The ground surface modeling of the Daliuta coal mine adopted a surface-data model and a TIN data structure. (4) 3D models of coal seams and rock formations of the Daliuta mine are established, which provide a method for the simulation of complex surfaces of geologic bodies. In the end, the models are applied to the Daliuta coal mine and the result shows that better geological effects are obtained.展开更多
There are a large number of abandoned coalmines in China,and most of them are located around major coal-fired power stations,which are the largest emission sources of carbon dioxide(CO2).Considering the injection of C...There are a large number of abandoned coalmines in China,and most of them are located around major coal-fired power stations,which are the largest emission sources of carbon dioxide(CO2).Considering the injection of CO2 into abandoned coalmines,which are usually in the flooded condition,it is necessary to investigate the effect of CO2-water-coal interaction on minerals and pore structures at different pressures,temperatures and times.It reveals that the CO2-water-coal interaction can significantly improve the solubility of Ca,S,Mg,K,Si,Al,Fe and Na.By comparing the mineral content and pore structure before and after CO2-water-coal interaction,quartz and kaolinite were found to be the main secondary minerals,which increased in all samples.The structures of micropores and mesopores in the range of 1.5-8 nm were changed obviously.Specific surface areas and pore volumes first increased and then decreased with pressure and time,while both increased with temperature.By using the Frenkel-Halsey-Hill model,the fractal dimensions of all samples were analyzed based on D(s1)and D(s2),which reflected the co mplexities of the pore surface and pore volume,respectively.The re sults show that fractal dimensions had very weak positive correlations with the carbon content.D(s1)had a positive correlation with the quartz and kaolinite contents,while D(s2)had a negative correlation with the quartz and kaolinite contents.展开更多
Hydraulic fracturing has been applied to enhance CBM production and prevent gas dynamical hazard in underground coal mines in China.However,affected by in situ stress orientation,hydrofracture can hardly continuously ...Hydraulic fracturing has been applied to enhance CBM production and prevent gas dynamical hazard in underground coal mines in China.However,affected by in situ stress orientation,hydrofracture can hardly continuously propagate within coal seam but may easily extend to the adjacent roof-floor strata,causing ineffective permeability enhancement in coal seam and increasing the risk of gas transfinite during mining coal.Thus,it is very necessary to artificially control the propagation direction of hydrofracture and make it well-aligned in large scale in coal seam.In this study,a method for controlling propagation direction of hydrofracture by multi-boreholes is investigated by theoretical analysis,laboratory experiment and numerical simulation.And this is followed by an on-site test in an underground coal mine to verify this method.Firstly,stress intensity factor at the hydrofracture tip is analyzed where pore pressure is taken into consideration.Results show that the pore pressure is able to increase the stress intensity factor and reduce hydrofracture propagation pressure.Based on this,a method of hydraulic fracturing using multi-boreholes to control hydrofracture direction is proposed.Afterwards,laboratory experiments are conducted to explore the impact of pore pressure on hydrofracture propagation.The experimental results agree with the theoretical analysis very well.Later on,a series of numerical simulations are performed to examine the influence of principal stress difference,the angle between assistance drillholes and the maximum principal stress,and the fluid pressure of the assistance drillholes on hydrofracture propagation.Finally,an on-site test in an underground coalmine is practiced where this proposed method is used to enhance the CBM production.Results show the scope of the hydro-fracture resulting from the multi-boreholes hydraulic fracturing method increases 2.7 times compared with that of conventional hydraulic fracturing.And gas production rate also increases 4.1 times compared with that of conventional hydraulic fracturing and 12.3 times compared with direct borehole extraction without fracturing.展开更多
A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source ...A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz. A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB(A) in the daytime from 69.8dB(A) and to 48.4dB(A) at night from 65.8dB(A).展开更多
In discussing coal mine entry construction with rock bolt technology, examinedthe craft and machinery problems as well as the conditions in which to use each kind ofmachine and tool.It exposed the intrinsic flaws of t...In discussing coal mine entry construction with rock bolt technology, examinedthe craft and machinery problems as well as the conditions in which to use each kind ofmachine and tool.It exposed the intrinsic flaws of the widely used road header.The problemis that it was designed according to early timbering support state but is not suitable forrock bolt technology.The way to improve the function of existing road headers is notthrough parallel operations but using the SUDM (Shield Union Driving Machine), which isa new machine that improves construction.This article proposed a few solutions in designto solve this problem.展开更多
To keep coal workers away from the hazardous area with frequent accidents such as the roof fall and rib spalling in an underground coalmine,we put forward the solution with robotized self-moving anchor-supporting unit...To keep coal workers away from the hazardous area with frequent accidents such as the roof fall and rib spalling in an underground coalmine,we put forward the solution with robotized self-moving anchor-supporting unit.The existing research shows that the surrounding rock of the roadway has self-stability,and the early or late support is not conducive to the safe and reliable support of the roadway,so there is a problem of support opportunity.In order to study the supporting effect and the optimal supporting time of the above solution,we established the mechanical coupling model of surrounding rock and advance support,and investigated the surrounding rock deformation and advance support pressure distribution under different reserved roof subsidence by using the numerical simulation software FLAC3D.The results show that the deformation of surrounding rock increases and finally tends to a stable level with the increase of pre settlement of roadway roof,and when the pre settlement of roof is between 8-15 mm,the vertical pressure of the top beam of advance support reaches the minimum value,about 0.58 MPa.Based on the above research,we put forward the optimum supporting time in roadway excavation,and summarized the evaluation method based on the mechanical coupling model of surrounding rock-advance support.展开更多
基金Supported by Guangdong Science and Technology Plan Project(2010B0318000112012A030700006)~~
文摘ln order to appraise scientifical y the heavy metal contamination in waste-land of coalmine tailing in Mingshan of Guangdong, the 5 soil samples in wasteland of coalmine tailing were col ected in November 2010 to March 2011. The 7 heavy metals content in the contaminated soil was measured by atomic absorption spec-trophotometry. The results showed the pH of the wasteland soil ranged from 2.87 to 6.16, and the soil was relatively infertile. The soil was mainly pol uted by Cd and Mn. The Cd content in wasteland soil ranged from 0.759 mg/kg to 3.109 mg/kg with an average content of 2.052 mg/kg, which was much higher than the standard content. The Mn content ranged from 387.057 to 488.660 mg/kg with an average content of 421.215 mg/kg, which was much higher than the standard content. The Nemerow integrated pol ution indexes showed the sample 1, sample 4 and sample 5 were of heavy pol ution, and sample 2 and sample 3 were of moderate pol ution.
文摘The changes of vegetation compositions, plant species diversity, species important value and succession of plant community were studied on waste dumps in Haizhou opencast coalmine which is located in the west of Liaoning Province, China (41°41(-42°56( N, 121°1(-122°56(E). Four kinds of terraces with different ages (5, 10, 20 and 40 years) were selected for investigation of plants. Total of 63 species of natural colonized plants were recorded on the waste dump and they belong to 23 families. The main families were Compositae (15 species), Fabaceae (11 species) and Leguminosae (8 species), which accounted for 54.0% of total species and play an important role in natural vegetation recovery in waste dump area. The dominant species on 5-, 10-, 20-, 40-year-old terraces were Tribulus terrestris + Echinochloa hispidula + Salsola collina, Echinochloa hispidula + Artemisia sieversiana + Artemisia scoparia, Echinochloa hispidula + Clinelymus dahuricus + Artemisia scoparia + Artemisia sieversiana + Melilotus officinalis, Clinelymus dahuricus+Phragmites communis + Echinochloa hispidula+ Setaria viridis, respectively. According to the important value of species calculated. It is determined that Tribulus terrestris can act as pioneer species on waste dump and Clinelymus dahuricus, Phragmites communis and Echinochloah hispidula are important dominant species in vegetation restoration in Haizhou opencast coalmine. The study results can provide scientific basis for selecting and disposing appropriately plant species and rehabilitating vegetation on waste dumps of coalmine.
基金supported by the Institute of Seismology Foundation, China Earthquake Administration (201326126)
文摘The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.
基金the framework of the research plan:physical and environmental processes in lithosphere induced by anthropogenic activities (AV0Z30860518)
文摘This paper describes the procedures for design of supports and stabilization measures in the roadways.The procedures are based on the system developed in Ostrava-Karvina coal basin in Czech Republic.The calculation of load bearing capacity of roadway supports contains the period of roadway construction and mining in the vicinities,based on the size of the natural rock arch.The loading of supports during mining comes from a stress wave in the rock mass in the forefront of coalface and the caving area of mined-out panel.The input data for the calculation method are deduced according to in-situ measurements of convergence and displacement in the roadways.
基金financially supported by the National Natural Science Foundation of China (grant No. 41602173)the Anhui University Ph. D Start-up Foundation (grant No. J10113190091)
文摘Objective Material exchange between magma and coal has recently received much attention, with published studies dedicated mainly to intrusion-related geochemical anomalies(An et al., 2017). It is found that magmatism not only alters the chemical compositions of coal seams, but also brings new minerals to natural coke. Although some studies have related magmatic water to secondary minerals in the natural coke, the mineral formation
基金Supported by the National Natural Science Foundation of China (505740720,50874089)the National Natural Science Foundation of Shannxi Province(2006E203)
文摘The forms of roof break,roof fall,and effects of the region scope in a fully mechanizedtop-coal caving (FMTC) face of the 101 fully-mechanized top coal caving face ofthe Tingnan Coalmine were analyzed by UDEC and FLAC^(3D) software.The analysis resultconfirms the phenomenon of roof falling,roof-off-strata,roof breaking,first weighting,periodicweighting and stress concentration,redistributions of surrounding rock and so on.Itprovides the gist to analyze the law of roof movement,characteristic of confining pressure,and to determine the formative structure forms of the immediate roof and main roof duringthe caving process.These results and the underground pressure observation results are inagreement.
文摘The present study reflects upon the results of substantial program of two-dimensional Finite Element Method （FEM） numerical analyses of the open pit that links to slope angle optimization associated with the safety factor of the pit slope of a coal mine in Bangladesh. In the present analyses, two types of models have been presented. The first model estimates safety factor without seismic effect on the overall pit slope of the model; the second model incorporates safety factor with seismic stability of the model. The calculated optimum slope angle of the first model is 31% with a rational safety factor of 1.51, prior to the seismic effect. However, the value is reduced to 0.93, 0.82, and 0.72, after we applies the seismic effect in the second model with M6, M6.5, and M7, respectively. Finally, our modeling results emphasize that for the case of the proposed Phulbari coalmine, there is extremely high prospect for causing massive slope failure along the optimum pit slope angle with 31% if the mine area felt seismic shaking, like the Sikkim （in northern India） earthquake with M6.9 on September 18, 2011.
基金Supported by the National Natural Science Foundation of China(40872103)
文摘The occurrence state of methane is mostly controlled by coalfield geologicalstructures.The coal-bearing strata at Qidong coalmine experienced many tectonic cyclessince their formation.The gas content made by the complicated structural geologic systemat the coalfield is very different, which is obviously higher on the north side of the Weimiaofracture belt than that on the south side and near itself.This thesis discussed the gas occurrenceregularity based on the geometric characteristics of the geological structure andits regional tectonic evolution.This study can provide a foundation for coalfield exploitationand deal with coal and gas outburst.
文摘The ventilation system plays an essential role in underground workings, and improvements in dilution effect to stochastic methane build-up at cul-de-sac of a coalmine require the installation of mixed ventilation system. For 4-12-1 I N02.8A centrifugal ventilation fan, the characteristic operating function of its mixed ventilation system is calculated from ventilation quantity and total pressure in the actual working status. At cul-de-sac of the reference coalmine, the evolution of methane concentration is a compound Poisson process and equivalent to a Brownian motion for Gaussian distributed increments. Solution of stochastic differential equation driven by mixed ventilation system, with dilution equation for its closure, provides parameters of mine ventilation system for keeping methane concentration within the permissible limit at cul-de-sac of the reference coalmine. These results intend to shed some light on application of blowing-sucking mixed ventilation systems in underground workings, and establish stochastic trends to consider methane control in coalmines.
基金support from the State Administration of Foreign Experts Affairs,China,for the research project "Risk assessment of CO 2 injection processes in carboniferous formations" at State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Science and Technology (Beijing)
文摘Over the last decades,people from almost all over the world have realized that it is necessary to quickly develop strategies for the control and reduction of greenhouse gases (GHG) emissions.Among various GHGs,carbon dioxide (CO2) is the most abundant GHG.Its underground storage involves less risk and lower levels of dangerousness.The paper briefly describes the most effective technologies available in the market for background processes to storage (capture and transport) CO2,as well as the more secure solutions for its storage,in particular for the geological storage in carboniferous formations.This paper also outlines the methodologies for the risk assessment involved in storage of CO2,with a particular focus on cases where the injection is made into unminable coal seams and in abandoned coalmines.Methodologies used for risk analysis are described in detail with particular emphasis on Bayesian network (BN).Some applications regarding the risk assessment of CO2 injection processes and CO2 storage in carboniferous formations and contamination of aquifers are presented and analyzed.Finally,based on the applications of BN,several conclusions are drawn.
基金Supported by the National Natural Science Foundation of China （50805010） the Natural Science Foundation of Shaanxi Province （2011JM70 17）
文摘In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.
文摘Data modeling is the foundation of three-dimensional visualization technology. First the paper proposed the 3D integrated data model of stratum, laneway and drill on the basic of TIN and ARTP, and designed the relevant conceptual and logical model from the view of data model, and described the data structure of geometric elements of the model by adopting the object-oriented modeling idea. And then studied the key modeling technology of stratum, laneway and drill, introduced the ARTP modeling process of stratum, laneway and drill and studied the 3D geometric modeling process of different section laneways. At last, the paper realized the three-dimensional visualization system professionally coalmine-oriented, using SQL Server as background database, Visual C＋＋6.0 and OpenGL as foreground development tools.
基金Project 2002CB412601 supported by Chinese Ministry of Science and Technology
文摘3D visualization is one of major problems in “Digital Mine” theory and its technological research field. Through the observation of 3D geological models, spatial structural information, connected with the information of production management hidden in geological data, could be detected. In order to meet the requirement of more efficient coal exploration, a case study of geological characters of the Daliuta Coal Mine is presented in which 3D visual models of the ground surface and geologic bodies are established on the basis of data models and data structures of 3D geology modeling. The main conclusions of this study are as follows: (1) Through analysis and organization of spatial discrete data, the drillhole database is designed with the data of the Daliuta mine; the connections amomg drillhole data are real- ized and displayed in a 3D environment. (2) Combining real data of the Daliuta mine, drillhole visualization is realized in a 3D environment by using the CoalMiner system. (3) The ground surface modeling of the Daliuta coal mine adopted a surface-data model and a TIN data structure. (4) 3D models of coal seams and rock formations of the Daliuta mine are established, which provide a method for the simulation of complex surfaces of geologic bodies. In the end, the models are applied to the Daliuta coal mine and the result shows that better geological effects are obtained.
基金The National Key Research and Development Plan(Grant No.2016YFC0501104)the National Natural Science Foundation of China(Grant Nos.51522903 and 51479094)。
文摘There are a large number of abandoned coalmines in China,and most of them are located around major coal-fired power stations,which are the largest emission sources of carbon dioxide(CO2).Considering the injection of CO2 into abandoned coalmines,which are usually in the flooded condition,it is necessary to investigate the effect of CO2-water-coal interaction on minerals and pore structures at different pressures,temperatures and times.It reveals that the CO2-water-coal interaction can significantly improve the solubility of Ca,S,Mg,K,Si,Al,Fe and Na.By comparing the mineral content and pore structure before and after CO2-water-coal interaction,quartz and kaolinite were found to be the main secondary minerals,which increased in all samples.The structures of micropores and mesopores in the range of 1.5-8 nm were changed obviously.Specific surface areas and pore volumes first increased and then decreased with pressure and time,while both increased with temperature.By using the Frenkel-Halsey-Hill model,the fractal dimensions of all samples were analyzed based on D(s1)and D(s2),which reflected the co mplexities of the pore surface and pore volume,respectively.The re sults show that fractal dimensions had very weak positive correlations with the carbon content.D(s1)had a positive correlation with the quartz and kaolinite contents,while D(s2)had a negative correlation with the quartz and kaolinite contents.
基金This paper is supported by the National Science Foundation of China(No.51604051)the National Science Foundation of Chongqing(No.cstc2018jcyjA2664)the China Scholarship Council(No.201708500037).
文摘Hydraulic fracturing has been applied to enhance CBM production and prevent gas dynamical hazard in underground coal mines in China.However,affected by in situ stress orientation,hydrofracture can hardly continuously propagate within coal seam but may easily extend to the adjacent roof-floor strata,causing ineffective permeability enhancement in coal seam and increasing the risk of gas transfinite during mining coal.Thus,it is very necessary to artificially control the propagation direction of hydrofracture and make it well-aligned in large scale in coal seam.In this study,a method for controlling propagation direction of hydrofracture by multi-boreholes is investigated by theoretical analysis,laboratory experiment and numerical simulation.And this is followed by an on-site test in an underground coal mine to verify this method.Firstly,stress intensity factor at the hydrofracture tip is analyzed where pore pressure is taken into consideration.Results show that the pore pressure is able to increase the stress intensity factor and reduce hydrofracture propagation pressure.Based on this,a method of hydraulic fracturing using multi-boreholes to control hydrofracture direction is proposed.Afterwards,laboratory experiments are conducted to explore the impact of pore pressure on hydrofracture propagation.The experimental results agree with the theoretical analysis very well.Later on,a series of numerical simulations are performed to examine the influence of principal stress difference,the angle between assistance drillholes and the maximum principal stress,and the fluid pressure of the assistance drillholes on hydrofracture propagation.Finally,an on-site test in an underground coalmine is practiced where this proposed method is used to enhance the CBM production.Results show the scope of the hydro-fracture resulting from the multi-boreholes hydraulic fracturing method increases 2.7 times compared with that of conventional hydraulic fracturing.And gas production rate also increases 4.1 times compared with that of conventional hydraulic fracturing and 12.3 times compared with direct borehole extraction without fracturing.
文摘A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz. A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB(A) in the daytime from 69.8dB(A) and to 48.4dB(A) at night from 65.8dB(A).
文摘In discussing coal mine entry construction with rock bolt technology, examinedthe craft and machinery problems as well as the conditions in which to use each kind ofmachine and tool.It exposed the intrinsic flaws of the widely used road header.The problemis that it was designed according to early timbering support state but is not suitable forrock bolt technology.The way to improve the function of existing road headers is notthrough parallel operations but using the SUDM (Shield Union Driving Machine), which isa new machine that improves construction.This article proposed a few solutions in designto solve this problem.
基金National Key Basic Research and Development Program Fund project(Grant No.2014CB046306)the Central University Funding Project for Basic Scientific Research Operations(Grant No.2009QJ16)
文摘To keep coal workers away from the hazardous area with frequent accidents such as the roof fall and rib spalling in an underground coalmine,we put forward the solution with robotized self-moving anchor-supporting unit.The existing research shows that the surrounding rock of the roadway has self-stability,and the early or late support is not conducive to the safe and reliable support of the roadway,so there is a problem of support opportunity.In order to study the supporting effect and the optimal supporting time of the above solution,we established the mechanical coupling model of surrounding rock and advance support,and investigated the surrounding rock deformation and advance support pressure distribution under different reserved roof subsidence by using the numerical simulation software FLAC3D.The results show that the deformation of surrounding rock increases and finally tends to a stable level with the increase of pre settlement of roadway roof,and when the pre settlement of roof is between 8-15 mm,the vertical pressure of the top beam of advance support reaches the minimum value,about 0.58 MPa.Based on the above research,we put forward the optimum supporting time in roadway excavation,and summarized the evaluation method based on the mechanical coupling model of surrounding rock-advance support.
